<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>demo06边框</title>
    <style>
        #d1 {
            width: 200px;
            height: 200px;
            background-color: lightgreen;
            border: 2px double red;
            border-radius:30px;
            border-radius:100px
        }

        #d2 {
            width: 200px;
            height:100px;
            background-color: blue;
            border-radius:50px;
        }

        #d3 {
            width: 200px;
            height: 100px;
            background-color: magenta;
            border-radius: 100px/50px ;
        }
        </style>
</head>
<body>
<div id="d1"></div>
<div id="d2"></div>
<div id="d3"></div>
<div id="d4"></div>
</body>
</html>